1. Field of the Invention
This invention relates to a vibration preventing device for detecting camera shake occurring before photographing and effecting the correction thereof, and a photographing apparatus having the vibration preventing function.
2. Related Background Art
Generally, when photographing with a camera held in hands, particularly when a lens of a long focal length is used or a low shutter speed is used, camera shake is liable to occur and thus, the quality of resulting photographs is spoiled. In order to prevent such camera shake and eliminate the deterioration of the quality of photographs, a vibration preventing device has been proposed.
FIG. 9 of the accompanying drawings shows the general construction of the vibration preventing device. In FIG. 9, the reference numeral 1 designates an interchangeable lens, and the reference numeral 2 denotes a camera body.
The interchangeable lens 1 has a photo-taking optical system comprising a fixed lens unit L1, a lens unit L2 movable in the direction of the optical axis thereof and governing focusing, and a vibration correcting lens unit L3 (a vibration correcting optical unit) adapted to shift in a direction perpendicular to the optical axis and effect vibration correction. Herein, the vibration correcting lens unit L3 assumes the construction of the rearmost lens unit of the photo-taking optical system, but is not restricted to this type of optical system.
A vibration detecting device 3 is comprised of a speed sensor or an angular speed sensor, and outputs a signal conforming to detected vibration. In FIG. 9, the vibration detecting device 3 is provided in the interchangeable lens 1, but in some cases, it is provided in the camera body 2.
A vibration correcting device 4 constitutes a shifting mechanism for moving the vibration correcting lens unit L3 on a plane perpendicular to the optical axis. The vibration correcting device 4 is not limited to one which shifts the vibration correcting lens unit in a direction perpendicular to the optical axis to thereby effect correction, but may be one which inclines the vibration correcting lens unit with respect to the optical axis to thereby effect correction.
A vibration controlling device 5 is provided in the interchangeable lens 1 and the memory portion thereof stores therein lens information such as a focal length and information about vibration correction. This vibration controlling device 5 controls the driving of the vibration correcting device 4 on the basis of the information stored in the memory portion thereof and the output of the vibration detecting device 3 to thereby effect vibration correction.
Such vibration correction is started by the operation of a vibration correction starting switch. As the vibration correction starting switch, there is known, for example, a construction provided on a manual focusing ring or a zoom ring (see Japanese Utility Model Application No. 4-62851).
However, in the above-described vibration proofing device according to the prior art, when the vibration correction starting switch is touched by mistake, vibration correction is sometimes started against a photographer's intention, and this has been very inconvenient during effecting a pan shot or the like.
Also, in the vibration preventing device according to the prior art, when a heavy lens is used, the position of the left hand holding that lens is naturally determined and there has been a case where operability is not preferable even though the vibration correction starting switch is provided on the manual focusing ring or the zoom ring.
On the other hand, as photographing apparatuses represented by cameras, ones provided with an autofocusing (AF) device have become popular. Further, it has been proposed to add a vibration preventing device for correcting camera shake during photographing in such an AF device. This vibration preventing device, as described above, is a device for detecting any fluctuation of the angle of the optical axis caused by camera shake or the like, and correcting the image vibration of a photographed image on the basis of the result of the detection, and as such device, there are known, for example, Japanese Patent Application Laid-Open No. 2-66535 (an example of a single-lens optical system), Japanese Patent Application Laid-Open No. 2-183217 (an example of the image correction by the shift of a portion of the photo-taking optical system of an internal focusing type telephoto lens), etc.
On the other hand, a half-depression timer has been carried on such a photographing apparatus. This half-depression timer is a device for starting a photographing preparatory operation by the closing of a half-depression switch, thereafter counting the time for which the OFF state of the half-depression switch continues, and stopping the photographing preparatory operation of the photographing apparatus when the counted time reaches a set time.
Also, this photographing apparatus has been provided with a vibration correction operating switch for instructing to start or stop vibration correction.
Further, there has been the possibility that when a vibration correction switch is inadvertently closed or the vibration correction switch is closed before the start of the photographing preparatory operation, a meaningless vibration correcting operation is performed to give birth to wasteful power source consumption.
In the above-described photographing apparatus according to the prior art, however, when vibration correction is selected by the vibration correction operating switch and the half-depression timer is started during the execution of vibration correction, the photographing preparatory operation of the photographing apparatus is stopped with the termination of the half-depression timer, but when vibration correction is to be stopped, it has been necessary for the user of the photographing apparatus to operate the vibration correction operating switch again to thereby stop vibration correction. This has led to the problem that the photographer's operation is cumbersome and moreover unnecessary electric power consumption takes place.
Also, when vibration correction is selected by the vibration correction operating switch and the half-depression timer is started during the execution of vibration correction and the half-depression timer is terminated, there is the possibility that in spite of vibration correction being effected, the photographing preparatory operation is terminated against the photographer's intention.
Further, the operation of stopping vibration correction and the timing for stopping could not be evenly determined by the photographer's level or liking.